I hate using McAfee . I am using a free version of Comodo firewall with the custom rulesets so that I can control which all software from my computer can connect to the internet. I am using a free version of Avira antivirus. Both the configuration runs fine on this computer without any performance issues.
At the office, we are using an enterprise version Norton Internet security and I recommend it as we are working in a high-risk environment.

SO the money you need to spend depends on many factors. If you are using it for home use no need to worry about using an updated security software with free versions.